Sawmill

ABSTRACT

A set of log support carriage units are supported for horizontal movement by a set of parallel spaced tubular tracks and are connected by an elongated hydraulic cylinder. The carriage units include depending plate-like brackets which support corresponding dog members for engaging the opposite ends of a log when the connecting cylinder is retracted. The main carriage unit includes a variable speed hydraulically driven resilient wheel. The wheel engages the bottom surface of one of the tracks and is effective to move both of the carriage units along the tracks for feeding the log into a pair of rotary saws of a corresponding set of laterally adjustable saw husks. The dog member of the main carriage unit is mounted on one end of an elongated horizontal shaft rotatably supported by the corresponding bracket. The opposite end of the shaft connects with a hydraulic motor which is also supported by the bracket and is controlled by valves positioned adjacent a rotary actuator driven by the shaft through an electrically actuated clutch. The log is rotated to a selected position for the initial cutting operation and is then automatically indexed by precisely 90* from the initial cutting position.

United States Patent Hartzell et a1.

1*June 17, 1975 Assignee:

Notice:

Filed:

Appl. No.: 365,859

SAWMILL Inventors: George W. Hartzell; Robert J.

Gunnerman, both of Piqua, Ohio Hartzell Industries, Inc., Piqua,

Ohio

The portion of the term of this patent subsequent to July 24, 1990, has been disclaimed.

June 1, 1973 1973, which is a continuation-in-part of Ser. No. 152,751, June 14, 1971, Pat. No. 3,747,455.

US. Cl. 83/708; 83/712; 83/425.3;

Int. Cl B27b 7/04; B27b 29/08 Field of Search 83/403.l, 404.4, 435.1,

References Cited UNITED STATES PATENTS Beck et al 83/435.l Crosby 83/404.4 Hargan et al. 83/409 Hartzell Hartzell -et al. 83/70 3,786,712 1/1974 Mackin 83/708 Primary Examiner-Donald R. Schran Attorney, Agent, or Firm-Jacox & Meckstroth ABSTRACT A set of log support carriage units are supported for horizontal movement by a set of parallel spaced tubular tracks and are connected by an elongated hydraulic cylinder. The carriage units include depending plate-like brackets which support corresponding dog members for engaging the opposite ends of a log when the connecting cylinder is retracted. The main carriage unit includes a variable speed hydraulically driven resilient wheel. The wheel engages the bottom surface of one of the tracks and is effective to move both of the carriage units along the tracks for feeding the log into a pair of rotary saws of a corresponding set of laterally adjustable saw husks. The dog member of the main carriage unit is mounted on one end of an elongated horizontal shaft rotatably supported by the corresponding bracket. The opposite end of the shaft connects with a hydraulic motor which is also supported by the bracket and is controlled by valves positioned adjacent a rotary actuator driven by the shaft through an electrically actuated clutch. The log is rotated to a selected position for the initial cutting operation and is then automatically indexed by precisely 90 from the initial cutting position.

9'Claims, 10 Drawing Figures SHEET PMENFEBJUN 17 1975 PATENTEDJLIN 17 I975 SHEET SAWMILL RELATED APPLICATION This application is a continuation-in-part of Ser. No. 322.5 37 filed Jan. 10, 1973 which is a continuation-inpart of Ser. No. 152,751, filed June 14, 1971. now issued as U.S. Pat. No. 3,747,455.

BACKGROUND OF THE INVENTION In a sawmill for successively cutting or sawing a supply of logs, it has been found desirable to provide a carriage system which grips or engages opposite ends of each log and feeds the log at a controllable rate through a set of power driven saws. The saws are laterally adjustable for selecting the cross-sectional dimensions of the center cant or lumber which is cut from the log. This general form of sawmill is disclosed in U.S. Pat. Nos. 1,093,680 and 2,803,272.

It has also been found desirable for the sawmill, and particularly the log support carriage, to be extremely rigid and stable and be conveniently adjustable for accommodating logs of various lengths, such as from four feet to fifteen feet and logs of non-uniform diameter. In addition, the sawmill should provide for efficiently and rapidly loading the logs into the log supporting carriage in a successive manner and for rotating each log on the carriage to select the position where the initial parallel cuts are to be made through the log. After the initial cuts are made, it has also been found desirable to provide for rotating or indexing the log by precisely 90 for cutting another set of parallel faces located at right angles to the pair of parallel faces produced by the initial cuts. It is apparent from a study of the sawmill assemblies disclosed in the above patents, that each of these assemblies is lacking in providing one or more of the above desirable features.

SUMMARY OF THE INVENTION The present invention is directed to further improvements of a sawmill constructed in accordance with the disclosure of the above identified application and which provides all of the desirable features referred to above in order to provide for successively cutting or sawing a supply of logs with maximum efficiency in production. In addition, the improved sawmill of the invention has substantial rigidity, stability and flexibility for accommodating logs of varying lengths and sizes and for cutting each log to result in a relatively thin center portion of only a few inches.

The above features and advantages are provided by a sawmill structure which generally includes a set of log support carriages mounted on a pair of parallel spaced tubular tracks and connected by an elongated fluid cylinder which has a piston rod adjustably connected to one of the carriages. The carriage units are driven along the rails by a hydraulically driven resilient wheel mounted on the main carriage unit and engaging one of the tracks. Both of the carriage units include depending brackets which support corresponding rotatable dog members for engaging opposite ends of a log. The dog member supported by the main carriage unit, is mounted on one end of an elongated shaft which extends parallel to the tracks and has an opposite end coupled directly to the shaft of a hydraulic motor supported by the corresponding bracket. The motor driven shaft is also connected through an electrically actuated clutch to a parallel spaced control shaft which supports an actuating member for controlling a valve in the hydraulic line connected to the motor. The logs are loaded into the carriages by a log loading unit which provides for elevating, tilting and changing the angle of the log.

Other features and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary plan view of a sawmill constructed in accordance with the invention and with the log support carriage removed and portions of the carriage support track broken away;

FIG. 2 is a fragmentary section taken generally on the line 22 of FIG. 1;

FIG. 3 is a section of the main log support carriage unit as taken generally on the line 3-3 of FIG. 4;

FIG. 4 is an elevational view of the log support carriage units, with portions broken away;

FIG. 5 is a section showing the secondary log support carriage unit taken generally on the line 55 of FIG.

FIG. 6 is a plan view of the main carriage unit as taken generally on the line 6-6 of FIG. 4;

FIG. 7 is an enlarged vertical section of the log indexing control system shown in elevation in FIG. 4;

FIG. 8 is a view similar to FIG. 4 and showing a log support carriage system constructed according to a modification of the invention;

FIG. 9 is a section taken generally on the line 99 of FIG. 8; and

FIG. 10 is an elevational view of a log loading unit constructed in accordance with a modification of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sawmill system shown in FIGS. 1 and 2, is generally similar to the sawmill structure disclosed in the above identified patent application Ser. No. 152,751, but incorporates further improvements refined since the above application was filed. In general, a supply of logs are received by the sawmill on a horizontally extending deck conveyor 15 including parallel spaced horizontal rails 16 supported at longitudinal spaced intervals by a series of cross beams 17 (FIGS. 1 and 2) and corresponding sets of vertical columns 18 which rest on the floor. A pair of endless conveyor chains 20 have upper runs extending along the rails 16 and are directed around a corresponding set of sprockets 21 mounted on corresponding cross shafts 22 located at opposite ends of the rails 16. The shaft 22 (FIG. 2), is driven by a hydraulic motor 24 (FIG. 1) through a gear reduction unit 26 so that the supply of logs are successively fed laterally along the top of the rails 16.

A log transfer rotor 30 is positioned adjacent the inner end of the deck conveyor 15 and includes a rotary shaft 32 which extends parallel to the shaft 22 and supports a plurality of axially spaced transfer plates or elements 34. As shown in FIG. 2, each of the transfer elements 34 has a pair of diametrically concave surfaces 36 arranged at right angles to a pair of convex surfaces 37. Each set of axially aligned concave surfaces 36 of the rotor 30 define a recess or cavity for receiving a log from the deck conveyor 15. The log transfer rotor 30 is automatically operated in intermittent timed relation with the deck conveyor so that the logs on the deck conveyor 15 are successively transferred to a pair of log loading units 40 (FIGS. 1 and 2).

Each of the units 40 includes a generally V-shaped cradle member 42 positioned so that the axis or geometric centerline of each log is disposed substantially in a vertical center plane P. Each of the cradle members 42 is supported by a set of vertical telescopic tubes 44 which encloses a vertical hydraulic cylinder (not shown) for elevating the corresponding cradle member 42 when the cylinder is actuated. The outer stationary tubes 44 of the units 40 are rigidly connected by a horizontal beam 47 and are reinforced by a sloping brace member 48. The detail construction and operation of the deck conveyor 15, the log transfer rotor and the log loading units 40 is set forth in copending US. pa tent application Ser. No. 301,992 filed Oct. 30, 1972, now US. Pat. No. 3,835,978 and assigned to the assignee of the present invention.

As also shown in FIGS. 1 and 2, a set of elongated parallel spaced tubular tracks 52 and 54 extend horizontally above the log loading units 40 and are supported by a series of longitudinally spaced inverted U- shaped frame members 56 and a series of generally C- shaped frame members 58. The tubular track 52 (FIG. 3) has a rectangular cross-sectional configuration, and the tubular track 54 has substantially a square crosssectional configuration. Each of the frame members 56 and 58 is frabricated by welding steel beams and includes an upper head member 59 (FIG. 2) which supports a depending bracket 61 rigidly secured to the upper surfaces of the tracks 52 and 54 for supporting tracks in their horizontal parallel spaced relation. The parallel frame members 58 are used only in the log loading zone or area adjacent the deck conveyor 15 and the log loading units 40, and the corresponding head members 59 project in a cantilevered manner to support the tracks 52 and 54.

Referring to FIGS. 3 & 6, the tracks 52 and 54 support a primary or main log support carriage unit 65 which includes a set of parallel spaced longitudinal frame members 67 and 69 (FIG. 6) rigidly connected by a set of end cross-frame members 71. The frame members 67 support an upper set of rollers 73 (FIG. 6) which engage the upper flat surface of the track 54 and a lower set of rollers 74 which engage the bottom side of the track 54. The lower set of rollers 74 are vertically adjustable by adjusting corresponding adjustment screw 76 (FIG. 4) to assure that the upper set of rollers 73 are held in firm contact with the upper surface of the track 54. Another set of rollers 77 (FIG. 6) are supported by each end frame member 71 and are eccentrically adjustable for firmly engaging the opposite sides of the track 54.

On the other side of the carriage unit 65, another set of upper and lower rollers 73 (FIG. 3) are supported by the side frame member 69 and engage the upper and lower flat surfaces of the track 52. The lower set of rollers 73 are also supported by eccentrically adjustable shafts to assure firm engagement of the upper set of rollers 73 against the track 52 so that all of the rollers cooperate to provide the carraige unit 65 with rigid lateral and vertical stability relative to the tracks 52 and 54. A resilient drive wheel 80 (FIGS. 3 and 6) is supported between the carriage frame members 67 and is positioned to engage the bottom side of the track 54 between the rollers 74. The drive wheel 80 encloses a rotary hydraulic motor which has a shaft 82 (FIG. 4) through which hydraulic fluid is supplied to drive the wheel 80. The drive wheel is vertically adjustable (FIG. 4) to provide for urging the wheel 80 against the bottom surface of the track 54 with a predetermined pressure.

A pair of closely spaced elongated plates 84 (FIG. 4) project vertically downwardly from the end frame members 71 of the carriage unit 65 and are rigidly secured to the frame members 71 by a set of plates 86 sandwiched between the plates 84. The lower edges of the plates 84 are rigidly connected by an elongated horizontal tube 88 (FIG. 4) which encloses an elongated horizontal shaft 90 rotatably supported with its axis extending within the reference plane P. The forward end of the shaft 90 supports a circular dog member 92 incorporating a center point 93 surrounded by a set of radial wedge knives for engaging the center portion of one end of a log L, as will be explained later. The opposite or rearward end portion of the shaft 90 extends through a bearing 94 and is connected by a coupling 96 directly to the output shaft of a hydraulic motor 98 supported by a bracket 99 secured to the rearward end portions of the plates 84. The motor 98 may also be connected to the rearward end of the shaft 90 through a worm gear box which also serves to aid in locking the shaft and log L against free rotation. The bracket 99 also supports a control unit 100 which controls the supply of hydraulic fluid to the motor 98.

Referring to FIG. 7, the control unit 100 includes a shaft 102 which is supported by bearings 103 and is driven by the shaft 90 through a chain drive 104. An electromagnetic clutch 106 connects the shaft 102 to a shaft 108 rotatably supported by a set of bearings 109. A disc-like cam actuator 110 is mounted on the outer end portion of the shaft 108 and is adapted to actuate sequentially a series of peripherally spaced limit switches 112 each having a finely adjustable actuating arm supporting a roller 113 engaging the outer peripheral surface of the cam actuator 110. The switches l 12 are connected to control solenoid valves which, in turn, control the flow of hydraulic fluid through the motor 98 for rotating the shaft 90 and the log L. The valves also provide for positively locking the motor 98, as will be explained later. 7

As illustrated in FIG. 4 and FIG. 5, a secondary log support carriage unit is also supported by the tracks 52 and 54 for longitudinal movement and includes a set of side walls or frame members 126 and 127 which are rigidly connected by a base-type crossframe member 128 extending below the tracks 52 and 54. Each end portion of each side frame member 126 and 127 supports a set of upper and lower eccentrically adjustable rollers 131 which engage the upper and lower surfaces of the corresponding track. Another set of rollers 132 are mounted on each end portion of the cross-frame 128, also by eccentrically adjustable shafts, and are positioned to engage the opposite side surfaces of the track 54. The rollers 131 and 132 provide for precision rolling movement of the carriage unit 125 along the tracks 52 and 54 without any lateral and vertical play.

A pair of generally triangular plates 136 (FIGS. 4 and 5) depend downwardly from the cross frame member 128 of the carriage unit 125 in parallel spaced relation.

supporting a shaft 139. A dog member 140 is mounted on the inner end portion of the shaft 139 and is constructed similar to the dog member 92, for engaging the opposite end surface of the log L, as illustrated in FIG.

The main carriage unit 65 is connected to the carriage unit 125 by an elongated hydraulic cylinder 145 which has one end portion connected to the plate 86 of the carriage 65 by a pin 146. The cylinder 145 includes a piston rod 148 having an outer end portion connected to the depending plates 136 of the carriage unit 125 by a cross-pin 149. An elongated cantilevered arm 152 projects from the carriage unit 165 towards the carriage unit 125, and a bracket 153 connects the outer end portion of the arm 152 to the hydraulic cylinder 145. The bracket 153 supports the cylinder 145 in a horizontal position, and is especially helpful when the piston rod 148 is extended substantially to separate the carriage units 65 and 125 for receiving a log of substantial length.

Referring again to FIG. 1, a generally rectangular frame 160 is positioned below the carraige support tracks 52 and 54 and includes a pair of parallel spaced rails 162 which extend laterally in relation to the tracks 52 and 54. A pair of opposing saw husks 165 are mounted for individual traversing movement on the rails 162 and each saw husk 165 includes a main shaft 166 which has an inner end portion supporting a circular cutter or saw 168. The opposite or outer end portion of each shaft 166 is driven by a corresponding electrical motor 170 through a multiple V-belt drive 172.

The motor 170 is supported by the frame of the saw husk for lateral adjustment with the saw 168 as a unit relative to the overhead carriage support tracks 52 and 54. The lower leading edge portion of each saw 168 is confined between a set of stabilizing pads 174 each of which is precisely adjustable by rotation of a corresponding adjustment rod 176. Each of the saw husks 165 also incorporates an endless belt conveyor 180 which extends parallel to the corresponding saw 168 for delivering slabs or boards cut from a log to another corresponding endless belt conveyor 182 positioned to deliver the slabs or boards longitudinally to the discharge end of the sawmill.

As diagrammatically illustrated in FIGS. 2 and 3, electrical and hydraulic fluid supply lines (not shown) extend to the main carriage unit 65 and are supported by an articulated pantograph linkage system 185 which has one end pivotally connected to the carriage unit 65 by a bracket 186 projected outwardly from one side of the carriage unit. These electrical and fluid control lines provide for controlling the operation of the hydraulic motor within the carriage drive wheel 80, the log rotation motor 98, the cylinder 145 and the clutch 106 from a control console located at a remote opera tors or sawyers platform.

The embodiment of the sawmill system illustrated in the drawings, operates in the following manner. A log is transferred by the log transfer rotor 30 into the cradle members 42 of the log loading units 40 by rotating the rotor 30 through 180. The carriage units 65 and 125 are positioned at the log receiving station above the loading units 40, and the cradle members 42 are simultaneously elevated to positions where the geometric axis of the log is substantially aligned with the axis defined by the rotatable dog members 92 and 140 on the respective carriage units 65 and 125. The hydraulic cylinder 145 is then actuated to retract the piston rod 148 so that the dog members 92 and 140 are pressed or forced into the corresponding end surfaces of the log and firmly engage the log. With the magnetic clutch 106 disengaged, the hydraulic motor 98 is actuated to rotate the log L, through 360 if necessary, for selecting the initial cutting position. The motor 98 is then hydraulically locked by closing of the fluid supply and discharge lines with the valves 112. The drive wheel is driven so that the carriage units 65 and 125 move along the tracks 52 and 54 at a controlled speed for feeding the log L into the pair of rotating saws 168 which are prepositioned according to the size of the log and the desired location for the cuts through the log.

After one pass of the log through the saws 168, the carriage units and log are returned to a position forward of the saw husks 165, and the magnetic clutch 106 is energized to couple the shaft 102 to the shaft 108. The hydraulic motor 98 is then actuated with hydraulic fluid supplied through the hydraulic valve controlled by the limit switches 112. After the log rotating shaft and the control shaft 108 rotate precisely 90, the cam actuator closes the control switch 112 so that the valve closes, and the motor 98 is deenergized and hydraulically locked to secure the log in its 90 indexed position. The log is then fed again into the saws 168 for removing another set of slabs from the log and to produce a square cant which remains supported by the dog members 92 and 140. If it is desired to cut boards from the cant, the carriage units are retracted, and the saw husks are simultaneously adjusted inwardly through a double rack and pinion system, after which the cant is fed into the saws 168 to form a board from each side of the cant. As disclosed in the above application, vertically disposed edger saws may be supported by each of the saw husks 165 to provide for producing boards from each log with fewer passes. Referring to FIGS. 8-10 which show modifications of a saw 1 mill constructed in accordance with the present invention, a set of primary and secondary carriage units are constructed substantially the same as the carriage units 65 and 125 described above. Accordingly, corresponding components of the carriage units are identified with the same reference number with the addition of a prime mark following the number. As shown in FIG. 8, the primary carriage unit 65 includes a cross-frame member 71' which supports a bracket 192 for receiving one end of an elongated fluid or hydraulic cylinder 195. The cylinder 195 is supported along its length by an elongated bracket 198 formed by a pair of parallel spaced vertical side plates 199 rigidly connected by a bottom plate 201 defining a channel-like crosssectional configuration for receiving the cylinder 195. The enlarged end portions of the side plates 199 are rigidly secured to the carriage unit 65 between the horizontal tracks 52 and 54 so that the bracket 198 projects in a cantilevered manner from the carriage unit 65.

The hydraulic cylinder 195 slidably supports an elongated piston rod 204 which has an outer end portion connected by a cross-pin 206 to an elongated tubular housing 208 extending through the center of the secon dary carriage unit 125'. The housing 208 has a generally square cross-sectional configuration and is sufficiently large to receive the forward projecting end portion of the cylinder support bracket 198, as shown in FIG. 8. The parallel spaced side walls of the tubular housing 208 are provided with a series of longitudinally spaced sets of laterally aligned holes 21 1 for selectively receiving the cross-pin 206. The longitudinally spaced sets of holes 211 provide for connecting the outer end portion of the cylinder rod 204 to the carriage unit 125' at longitudinally spaced intervals. Thus by merely resetting the cross-pin 206, the relative normal spacing between the carriage units 65' and 125 can be conveniently and quickly changed for accommodating logs of substantial varying length, as for example, between four feet and sixteen feet in length. The extension of the piston rod 204 from the cylinder 195, cooperates with the adjustable connection of the piston rod to the carriage unit 125 to provide the substantial variation in the spacing between the carriage unit 65 and 125. To reduce the cantilevered projection of the cylinder support bracket 198, the bracket 198 and cylinder 195 may be recessed into the carriage unit 65'.

Referring to FIG. 10, in place of the log loading units 40 described above in connection with FIGS. 1 and 2, a single log loading unit 220 is positioned under the path of the carriage units. The unit 220 includes a base 222 which supports an outer cylindrical tube 224 in a vertical position. The outer tube 224 is reinforced by a set of inclined braces 226, and slidably supports an inner cylindrical tube 228. A circular plate 229 is rigidly secured to the upper end of the inner tube 228. The plate 229 connects with the upper end of a piston rod (not shown) projecting upwardly from a hydraulic cylinder 230 positioned concentrically within the sliding telescopic tubes 224 and 228. The lower end portion of the hydraulic cylinder 230 is supported by a bracket mounted on the base plate 222, and the cylinder 230 is controlled by hydraulic fluid supplied through a set of hydraulic fluid lines 232.

The plate 229 rotatably supports a plate 236 which rigidly connects a pair of parallel spaced angular shaped plates 238. An arcuate portion of the plate 236, includes gear teeth which are engaged by a pinion 239 mounted on the shaft of a reversible hydraulic motor 240 mounted on the upper end portion of the inner support tube 228. Actuation of the motor 240 is effective to cause rotation of the parallel side plates 238 by an angle of several degrees to either side from a normal position parallel to the path of the carriage units.

A generally V-shaped cradle member 242 is rigidly secured to the left ends (FIG. of the side plates 238 and has a configuration substantially the same as the cradle member 42 shown in FIG. 2. An arm 246 has one end pivotally connected by cross-pin 247 to the side plates 238, and its other end supports another cradle member 242. A generally vertical hydraulic cylinder 248 has its lower end pivotally connected by a cross-pin 249 to the depending lower end portions of the side plates 238. A piston rod 251 projects upwardly from the cylinder 248 and is pivotally connected to the outer end portion of the arm 246.

After a log L is received by the cradle members 242 from the log transfer rotor 30, the hydraulic cylinder 230 is actuated so that the cradle members 242 and the log are elevated to a position where the center of the left end (FIG. 10) of the log L is aligned with the dog member on the corresponding carriage unit. The cylinder 248 is then actuated to position the center of the opposite end of the log in horizontal alignment with the dog member on the adjacent carriage unit. The hydraulie cylinder 145 or 195 is then actuated so that the opposing dog members are forced into the opposite ends of the log L. If it is desired to rotate the log L by a slight angle on the vertical axis of the log loading unit 220, the hydraulic motor 240 is actuated in the appropriate direction so that the axis of the log is precisely aligned with the center line of the dog members on the carriage units. Instead of transferring a log directly from the rotor 30 into the cradle members 242, another set of cradle members may be positioned outboard of the cradle members 242 and supported directly from the floor at a slightly higher elevation. This additional set of cradle members will eliminate any shock or impact being received by the loading unit 220 when a log is transferred.

From the drawings and the above description, it is apparent that a sawmill system constructed in accordance with the present invention, provides desirable features and advantages. For example, the system provides for efficiently handling a supply of logs so that a high production rate is obtained. This is, while one log is being fed into the saws 168 by the carriage units 65 and 125, the next successive log is automatically transferred into the cradle members 42 of the log loading units 40 or the cradle members 242 of the log loading unit 220. Thus after sawing of the log supported by the carriage units is completed, and the center cant or board is released from the carriage units at the discharge end of the sawmill, the carriage units are returned to the log loading position. The next log is quickly loaded into the carriage units by elevating the cradle members 42 or 242 until the axis of the log aligns with the axis of the dog members 92 and 140. As mentioned above, the log loading units 40 or unit 220 are adapted to be operated to compensate for tapering logs by increasing the elevation of the cradle member supporting the smaller end portion of the log. The load loading unit 220 also provides for rotating the log on a vertical axis to obtain rapid alignment of the log.

Other important features are provided by the construction and support of the main carriage unit 65 or 65' and the slave or secondary carriage unit or 125'. That is, the mounting of the carriage units on the rigid tracks 52 and 54 provide each carriage unit with substantial vertical and horizontal rigidity and stability thereby assuring that the carriage units and the supported log move in a precise linear path without any chatter or rocking movement. The connection of the carriage units with the hydraulic cylinder or 195 also provides for gripping each log with a preselected force and for quickly accommodating logs of varying length. Furthermore, the cylinder 145 may be conveniently replaced by another cylinder of lesser or greater length or the piston rod 204 of the cylinder 195 may be repositioned for accommodating logs of substantially longer or shorter length. The cylinder 145 or 195 also provides for reducing the force exerted axially on a log by the dog members 92 and 140 as the remaining portion of the log becomes thinner so that the force does not produce bowing of this remaining portion of the log. In addition, the construction and support of the dog members 92 and 140 by the depending plates 84 and 136, respectively provide for progressively cutting a log with multiple passes through the saw husks until the thickness of the remaining center portion of the log is minimized to only a few inches. This enables each log to be efficiently converted into usable lumber.

Another important advantage is provided by the motor control actuator 110 (FIG. 7) which is driven from the log rotating shaft 90 through the clutch 106. As indicated above, with the clutch 106 disengaged, the operator or sawyer operates a push button which actuates the control valve in the hydraulic lines to the hydraulic motor 98 so that the log is rotated for selecting the initial cutting position which provides the most effective cutting of the log. After the initial cutting position is selected, the clutch 106 is engaged. Thus after the initial pass of the log through the saws 168, and the motor 98 is again actuated, the actuator 110 rotates with the shaft 90 and the log. When the log and shafts have rotated precisely 90, the flow of hydraulic fluid I through the motor 98 is stopped by automatic closing of the control valve through action of the limit switch 112 by the actuator 110. When the valve 112 closes, the motor 98 is hydraulically locked so that it prevents rotation or oscillation of the shaft 90 and log while the log is being fed into the rotating saws 168. I

While the forms of sawmill equipment herein described constitute a preferred embodiment of the invention, it is to be understood that the invention is not limited to these precise forms of equipment, and that changes may be made therein without departing from the scope and spirit of the invention.

The invention having thus been described, the following is claimed:

1. An improved sawmill adapted for efficiently cutting a successive supply of logs, comprising a set of elongated parallel spaced tracks, frame means supporting said tracks in horizontally spaced positions, a first carriage unit including a first set of wheels engaging said tracks in longitudinally spaced relation, said first set of wheels providing for independent longitudinal linear movement of said first carriage unit on said tracks, a second carriage unit including a second set of .wheels also engaging said tracks in longitudinally spaced relation, said second set of wheels providing for longitudinal linear movement of said second carriage unit along said tracks independent of said first carriage unit, an elongated extensible actuator connecting said first and second carriage units and providing for changing the space between said carriage units within a predetermined range relative to said tracks, said carriage units including means supporting a set of horizontally disposed opposing dog members adapted to engage opposite ends of each log, means for adjustably connecting said actuator to one of said carriage units to provide for changing said predetermined range, drive means for moving said carriage units along said tracks as a combined unit, laterally adjustable cutter means positioned adjacent the path of said carriage units for cutting the log, and a motor on at least one of said carriage units and having a rotary shaft connected to rotate the corresponding said dog member for positioning the log at a selected cutting position.

2. A sawmill as defined in claim 1 wherein said actuator comprises a fluid cylinder including a cylinder housing member enclosing a piston rod member, means for connecting one of said members to one of said carriage units, and said adjustably connecting means connects the other of said members to the other said carriage unit.

3. A sawmill as defined in claim 2 including a frame member secured to one of said carriage units and supporting said fluid cylinder housing member in a substantially horizontal position.

4. A sawmill as defined in claim 3 wherein the other said carriage unit includes means defining an opening for receiving said frame member.

5. A sawmill as defined in claim 4 wherein said means for receiving said elongated frame member, comprise an elongated support member, and means for connecting said piston rod member to said support member at longitudinally spaced positions.

6. A sawmill for cutting a successive supply of logs and including a set of elongated parallel spaced tracks, means supporting said tracks in substantially horizontal positions, carriage means mounted on said tracks for longitudinal movement and supported by a plurality of wheels engaging said tracks, said carriage means including a set of horizontally disposed opposing dog members adapted to engage opposite ends of each log, means for moving said carriage means along said tracks, said carriage means including means for rotating one of said dog members and the log engaged thereby, saw means supported for lateral adjustment relatively to the path of said carriage means, a set of horizontally spaced cradle members positioned below the path of said carriage means and adapted to receive a log, and means supporting said cradle members for generally vertical movement as a unit, the improvement including a frame member supporting one of said cradle members, a generally vertical first fluid cylinder connected to said frame member, an arm pivotally mounted on said frame member and supporting the other said cradle member for relative vertical movement, and a second fluid cylinder extending between said frame member and said arm and cooperating with said first fluid cylinder to provide for rapidly and precisely positioning each log relative to said opposing dog members on said carriage means.

7. A sawmill as defined in claim 6 including means for rotating said frame member on a generally vertical axis to facilitate rapid alignment of the log centerline with said opposing dog members.

8. In a sawmill for cutting a successive supply of logs and including a set of elongated parallel spaced tracks, means supporting said tracks in substantially horizontal positions, carriage means mounted on said tracks for longitudinal movement and supported by a plurality of wheels engaging said tracks, said carriage means including a set of horizontally disposed opposing dog members adapted to engage opposite ends of each log, means for moving said carriage means along said tracks, means for rotating one of said dog members and the log engaged thereby, and cutter means supported for lateral adjustment relatively to the path of said carriage means, the improvement wherein said means for rotating one of said dog members and the log engaged thereby comprise a motor carried by said carriage means and having a rotary output shaft, first drive means connecting said output shaft of said motor to said one dog member to produce rotation of said dog member and the log in response to actuation of said motor, said motor and said drive means providing for rotating the log continuously through 360 for selecting an initial cutting position, a rotary actuating member, means responsive to rotation of said actuating member for controlling the operation of said motor, second drive means for selectively rotating said actuating member in response rotation of said output shaft, and

l l said second drive means including a remotely controllable clutch cooperating with said actuating member to control said motor for producing precision rotation of the log from the selected initial cutting position.

further includes a shaft positioned substantially parallel 9. A sawmill as defined in claim 8 wherein said motor said actuating member is effective to actuate said valve.

comprises a hydraulic motor, said second drive means 

1. An improved sawmill adapted for efficiently cutting a successive supply of logs, comprising a set of elongated parallel spaced tracks, frame means supporting said tracks in horizontally spaced positions, a first carriage unit including a first set of wheels engaging said tracks in longitudinally spaced relation, said first set of wheels providing for independent longitudinal linear movement of said first carriage unit on said tracks, a second carriage unit including a second set of wheels also engaging said tracks in longitudinally spaced relation, said second set of wheels providing for longitudinal linear movement of said second carriage unit along said tracks independent of said first carriage unit, an elongated extensible actuator connecting said first and second carriage units and providing for changing the space between said carriage units within a predetermined range relative to said tracks, said carriage units including means supporting a set of horizontally disposed opposing dog members adapted to engage opposite ends of each log, means for adjustably connecting said actuator to one of said carriage units to provide for changing said predetermined range, drive means for moving said carriage units along said tracks as a combined unit, laterally adjustable cutter means positioned adjacent the path of said carriage units for cutting the log, and a motor on at least one of said carriage units and having a rotary shaft connected to rotate the corresponding said dog member for positioning the log at a selected cutting position.
 2. A sawmill as defined in claim 1 wherein said actuator comprises a fluid cylinder including a cylinder housing member enclosing a piston rod member, means for connecting one of said members to one of said carriage units, and said adjustably connecting means connects the other of said members to the other said carriage unit.
 3. A sawmill as defined in claim 2 including a frame member secured to one of said carriage units and supporting said fluid cylinder housing member in a substantially horizontal position.
 4. A sawmill as defined in claim 3 wherein the other said carriage unit includes means defining an opening for receiving said frame member.
 5. A sawmill as defined in claim 4 wherein said means for receiving said elongated frame member, comprise an elongated support member, and means for connecting said piston rod member to said support member at longitudinally spaced positions.
 6. A sawmill for cutting a successive supply of logs and including a set of elongated parallel spaced tracks, means supporting said tracks in substantially horizontal positions, carriage means mounted on said tracks for longitudinal movement and supported by a plurality of wheels engaging said tracks, said carriage means including a set of horizontally disposed opposing dog members adapted to engage opposite ends of each log, means for moving said carriage means along said tracks, said carriage means including means for rotating one of said dog members and the log engaged thereby, saw means supported for lateral adjustment relatively to the path of said carriage means, a set of horizontally spaced cradle members positioned below the path of said carriage means and adapted to receive a log, and means supporting said cradle members for generally vertical movement as a unit, the improvement including a frame member supporting one of said cradle members, a generally vertical first fluid cylinder connected to said frame member, an arm pivotally mounted on said frame member and supporting the other said cradle member for relative vertical movement, and a second fluid cylinder extending between said frame member and said arm and cooperating with said first fluid cylinder to provide for rapidly and precisely positioning each log relative to said opposing dog members on said carriage means.
 7. A sawmill as defined in claim 6 including means for rotating said frame member on a generally vertical axis to facilitate rapid alignment of the log centerline with said opposing dog members.
 8. In a sawmill for cutting a successive supply of logs and including a set of elongated parallel spaced tracks, means supporting said tracks in substantially horizontal positions, carriage means mounted on said tracks for longitudinal movement and supported by a plurality of wheels engaging said tracks, said carriage means including a set of horizontally disposed opposing dog members adapted to engage opposite ends of each log, means for moving said carriage means along said tracks, means for rotating one of said dog members and the log engaged thereby, and cutter means supported for lateral adjustment relatively to the path of said carriage means, the improvement wheRein said means for rotating one of said dog members and the log engaged thereby comprise a motor carried by said carriage means and having a rotary output shaft, first drive means connecting said output shaft of said motor to said one dog member to produce rotation of said dog member and the log in response to actuation of said motor, said motor and said drive means providing for rotating the log continuously through 360* for selecting an initial cutting position, a rotary actuating member, means responsive to rotation of said actuating member for controlling the operation of said motor, second drive means for selectively rotating said actuating member in response rotation of said output shaft, and said second drive means including a remotely controllable clutch cooperating with said actuating member to control said motor for producing precision rotation of the log from the selected initial cutting position.
 9. A sawmill as defined in claim 8 wherein said motor comprises a hydraulic motor, said second drive means further includes a shaft positioned substantially parallel to said output shaft and connected to said clutch, a valve connected to control the hydraulic fluid supplied to said motor, and said means responsive to rotation of said actuating member is effective to actuate said valve. 